ANTH 210 Lecture Notes - Lecture 17: Axial Tilt, Milankovitch Cycles, Late Pleistocene
3 May 2018
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Lecture'17'–'The'Mesolithic''
THE$HOLOCENE:$GLOBAL$WARMING$
• Paleoclimates+
o Holocene'Epoch'began'around'11,500'kya'&'continues'into'today'
§ Consists'of'significant'warming'of'the'planet.'
§ Large'debates'on'whether'we’ve'shifted'into'another'geological'epoch'
because'our'climate'has'changed'so'much.'
o Global'climate'begins'to'warm,'moderate'climates'by'9500'kya'
o Sea'levels'stabilize'to'modern'level'by'7000'BP'
o Upper'Pleistocene'had'been'the'coldest'period.'
o Milankovitch$Cycles$
§ Earth’s'glacial'&'interglacial'periods'within'the'Late'Pleistocene'have'
been'caused'primarily'by'cyclical'changes'in'the'Earth’s'circumnavigation'
of'the'Sun.''
§ These'changes'affect'the'seasonality'&'location'of'solar'energy'around'
the'Earth:'
• !""#$%&'"'%()
o Changes'to'the'shape'of'the'Earth’s'orbit'around'the'Sun.''
o Orbital'shape'ranges'between'more'and'less'elliptical'on'a'
cycle'of'about'100,000'years'(periodicity)'à'changes'the'
amounts'of'solar'radiation'we'receive'on'Earth.'
o Greater'variation'in'Sun’s'energy'reaching'the'Earth'when'
the'orbital'shape'is'more'elliptical.'
§ Circular'='fairly'consistent'amounts'of'radiation.'
§ Elliptical'='periods'of'large'distance'(little'radiation)'
• *+,'-.'%()/01'2,)3',%4)
o The'inclination'of'the'Earth’s'axis'in'relation'to'its'plane'of'
orbit'around'the'Sun.'
o Oscillations'in'the'degree'of'Earth’s'axial'tilt'occur'on'a'
periodicity'of'41,000'years'from'21.5'to'24.5'degrees.'
o Affects'the'severity'of'the'seasons.'
'
Document Summary
The holocene: global warming: paleoclimates, holocene epoch began around 11,500 kya & continues into today. Consists of significant warming of the planet. Earth"s glacial & interglacial periods within the late pleistocene have been caused primarily by cyclical changes in the earth"s circumnavigation of the sun. Circular = fairly consistent amounts of radiation. Usually due to a change in the amount of water in the basins: e. g. an addition of water from melting ice sheets. Also occurs during periods of warming because as the water heats, it expands. Causes a global rise or fall in sea level. This type of sea level change created the english channel. Isostatic change = describes when the earth"s crust rises or falls relative to the sea. Often due to an increase or decrease of mass on top of the crust. Causes a local change in sea level (locally derived process)
